The present invention relates to electronic parts such as a tip inductor used for eliminating an electro-magnetic interference generated within signal lines of electronic equipments, and a method and device for making same.
A number of such electronic parts for noise rejection and their methods of making have been proposed in the art, as in the following examples.
As a conventional example, Japanese Patent Kokai No. 67,910/1981 discloses an inductor made by loading ferrite powder in an extruding die in which a platinum coil has been arranged, pressing and sintering the ferrite to form a coil built-in magnetic material of integrally molded structure.
As an another conventional example, Japanese Patent Kokai No. 48,410/1983 discloses a method for making an inductor which comprises winding a conductive line on the periphery of a sintered magnetic bar to arrange a roughly wound part and a densely wound part thereon alternatively and continuously, coating a conductive paste on the roughly wound part to cover the periphery of the magnetic material so as to embed the conductive line therein, sintering thus covered bar and cutting the bar at the roughly wound part to fix external electrodes.
These conventional methods described above might provide electronic parts of generally required quality. In the case of the first example, however, such inductors are made as a batch-wise single part production which is not effective. On the other hand, according to the method described in the second example, it is difficult to make inductors on a high speed production process because of its roughly and densely winding system which should complicate related facilities. Further, the sintered product has undesirable magnetic properties due to residual inner stress and an uneven periphery surface.